# 笨办法学 Python 3
# 练习20：函数和文件
# data:2023.1.2

from sys import argv

script, input_file = argv

def print_all(f):
    print(f.read())

def rewind(f):
    f.seek(0)

def print_a_line(line_count,f):
    print(line_count,f.readline())

current_file = open(input_file)

print("首先，让我们打印整个文件：\n")

print_all(current_file)

print("Now let's rewind, kind or like a tape.")

rewind(current_file)

print("Let's print three lines:")

current_line = 1
print_a_line(current_line,current_file)

current_line = current_line + 1
print_a_line(current_line,current_file)

current_line = current_line + 1
print_a_line(current_line,current_file)